US4218878A - Acceleration monitoring system for protecting gas turbine against damaging operation at resonant speeds - Google Patents

Acceleration monitoring system for protecting gas turbine against damaging operation at resonant speeds Download PDF

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Publication number
US4218878A
US4218878A US05/900,946 US90094678A US4218878A US 4218878 A US4218878 A US 4218878A US 90094678 A US90094678 A US 90094678A US 4218878 A US4218878 A US 4218878A
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Prior art keywords
turbine
speed
generating
rated
actual
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Expired - Lifetime
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US05/900,946
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Roy W. Kiscaden
Kermit R. Wescott
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CBS Corp
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Westinghouse Electric Corp
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Priority to US05/900,946 priority Critical patent/US4218878A/en
Priority to CA315,558A priority patent/CA1110739A/en
Priority to GB7913131A priority patent/GB2020814B/en
Priority to BR7902432A priority patent/BR7902432A/en
Priority to JP54049185A priority patent/JPS581251B2/en
Priority to IT22041/79A priority patent/IT1112783B/en
Priority to AR276289A priority patent/AR221088A1/en
Priority to BE0/194893A priority patent/BE875924A/en
Application granted granted Critical
Publication of US4218878A publication Critical patent/US4218878A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02CGAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C7/00Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
    • F02C7/26Starting; Ignition

Definitions

  • the present invention relates to gas turbine controls and more particularly to gas turbine startup speed monitors.
  • the present invention is directed to achieving better turbine protection against resonant operation during startup.
  • Means are provided for generating an actual turbine speed signal and a reference speed signal which increases over time in accordance with the desired turbine startup speed profile. The two signals are compared and an alarm signal is generated if the difference reaches a first level and a turbine trip signal is generated if the difference reaches a second higher level.
  • FIG. 1 shows a block diagram of a turbine acceleration monitor system arranged in accordance with the principles of the invention.
  • FIG. 2 shows a desired turbine startup speed profile and a typical actual startup speed profile in which no alarm or trip is generated because actual speed is close enough to desired speed over the whole range.
  • FIG. 1 an acceleration monitoring system 10 for a gas turbine 12.
  • a fuel control 14 operates a throttle valve 15 in accordance with a stored fuel schedule which normally causes the turbine 12 to be energized such that it moves from ignition to synchronous speed in accordance with a desired speed profile. If the turbine 12 is slowed in its startup, as by override operation of a temperature limit control 16 or a surge limit control 18, the acceleration monitoring system 10 provides turbine protection by alarm and turbine trip actions under preset conditions.
  • Logic permissives must first exist before acceleration monitor protection becomes operational. Thus, in this case, a master sequence forcing relay 4X must first be on the turbine 12 must not be in the process of purging which occurs during multiple ignition attempts. In addition, turbine speed must be less than 98% rated. When the logic permissives are satisfied, AND block 22 generates an enabling signal for ramp control logic blocks 24, 26 and 28.
  • the actual turbine speed is indicated by a signal from a speed sensor 20. If the turbine speed is less than 63% rated speed, AND gate 24 operates switch 25. Similarly, AND gate 26 operates switch 27 when the turbine speed is between 63% and 90% rated and AND gate 28 operates switch 29 when the turbine speed is between 90% and 98% rated.
  • an amplifier 30 is connected as an integrator having a time constant determined by C 1 , R 1 , R 2 and R 3 .
  • the circuit is arranged to generate a speed versus time profile having three straight-line segments 25A, 27A and 29A which approximate the desired startup speed profile.
  • the absolute value of the difference between the speed reference and actual speed is calculated in block 32 and compared with individual alarm and trip setpoints in comparators 34 and 36.
  • AND gates 38 and 40 prevent alarms and trips when master relay 4X is not operated or when actual speed is greater than 98% rated.
  • Switch 62 resets the integrator and thus the speed reference to zero when master relay 4X drops out.
  • Switch 44 is closed when a fast start is required which increases the rate of all speed references.
  • the output from the amplifier represents the speed reference per ramps 27A and 29A, respectively, and the difference between the actual and reference speeds is compared to the alarm and trip setpoints.
  • the turbine accelerates along a speed profile such as the profile 46 in FIG. 2. If at any time the actual turbine speed drops to alarm profile 48, an alarm is generated. If the turbine speed drops to trip profile 50, the turbine 12 is tripped.
  • One main advantage of the described system is that it provides continuous monitoring of the startup acceleration profile without the use of multiple sequence timers. Further, acceleration is monitored with equal resolution at any discrete speed providing better accuracy than discrete sequence timers.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Turbines (AREA)
  • Control Of Velocity Or Acceleration (AREA)

Abstract

A fuel control schedules fuel to a gas turbine to produce a scheduled speed profile during startup. The scheduled speed profile is continuously compared to actual turbine speed during startup, and the difference is compared to an alarm setpoint and a trip setpoint. Normally, temperature and surge limit controls prevent the turbine from accelerating too fast; and, if the turbine is accelerating too slowly, an alarm output is generated when the actual/desired speed difference reaches the alarm setpoint and the turbine is tripped when the actual/desired speed difference reaches the trip setpoint.

Description

BACKGROUND OF THE INVENTION
The present invention relates to gas turbine controls and more particularly to gas turbine startup speed monitors.
In the operation of a power plant gas turbine, there are certain relatively narrow critical speed ranges where resonant conditions occur and costly stress damage or failure of blades and other parts can occur if the turbine is operated at those speeds for even relatively brief periods of time. Although turbine startup normally calls for smooth and continuous increasing speed from ignition to synchronism, the turbine may develop some problem or other circumstances may arise which cause the turbine temperature limit or surge control to hold the turbine at a particular speed for some time.
Protection has conventionally been provided against turbine operation at resonant speeds by the use of a plurality of sequence timers which cause the turbine to trip if the turbine fails to reach a designated higher speed from a designated lower speed within a preset time period measured by the timer associated with that part of the startup sequence. One difficulty with the sequence-timer approach is that the turbine may reach and operate at a critical speed during most of the measured time period, thereby creating the possibility that significant stress damage or part failure will occur before the turbine is signalled to trip by the timer.
SUMMARY OF THE INVENTION
The present invention is directed to achieving better turbine protection against resonant operation during startup. Means are provided for generating an actual turbine speed signal and a reference speed signal which increases over time in accordance with the desired turbine startup speed profile. The two signals are compared and an alarm signal is generated if the difference reaches a first level and a turbine trip signal is generated if the difference reaches a second higher level.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a block diagram of a turbine acceleration monitor system arranged in accordance with the principles of the invention.
FIG. 2 shows a desired turbine startup speed profile and a typical actual startup speed profile in which no alarm or trip is generated because actual speed is close enough to desired speed over the whole range.
DESCRIPTION OF THE PREFERRED EMBODIMENT
More particularly, there is shown in FIG. 1 an acceleration monitoring system 10 for a gas turbine 12. A fuel control 14 operates a throttle valve 15 in accordance with a stored fuel schedule which normally causes the turbine 12 to be energized such that it moves from ignition to synchronous speed in accordance with a desired speed profile. If the turbine 12 is slowed in its startup, as by override operation of a temperature limit control 16 or a surge limit control 18, the acceleration monitoring system 10 provides turbine protection by alarm and turbine trip actions under preset conditions.
Logic permissives must first exist before acceleration monitor protection becomes operational. Thus, in this case, a master sequence forcing relay 4X must first be on the turbine 12 must not be in the process of purging which occurs during multiple ignition attempts. In addition, turbine speed must be less than 98% rated. When the logic permissives are satisfied, AND block 22 generates an enabling signal for ramp control logic blocks 24, 26 and 28.
The actual turbine speed is indicated by a signal from a speed sensor 20. If the turbine speed is less than 63% rated speed, AND gate 24 operates switch 25. Similarly, AND gate 26 operates switch 27 when the turbine speed is between 63% and 90% rated and AND gate 28 operates switch 29 when the turbine speed is between 90% and 98% rated.
Generally, an amplifier 30 is connected as an integrator having a time constant determined by C1, R1, R2 and R3. In this instance, as shown in FIG. 2, the circuit is arranged to generate a speed versus time profile having three straight- line segments 25A, 27A and 29A which approximate the desired startup speed profile.
The turbine mechanical designers normally specify the desired turbine startup speed profile which will provide long turbine life. As already indicated, one problem has been that although existing turbine controls have generally provided for startup acceleration, they have not provided adequate protection against a turbine hold at a resonant speed.
During the first speed range, current flows through resistor R1 to the integrating capacitor C1 in proportion to the supply voltage and the value of R1. The output speed reference rises per ramp 25A.
The absolute value of the difference between the speed reference and actual speed is calculated in block 32 and compared with individual alarm and trip setpoints in comparators 34 and 36. AND gates 38 and 40 prevent alarms and trips when master relay 4X is not operated or when actual speed is greater than 98% rated. Switch 62 resets the integrator and thus the speed reference to zero when master relay 4X drops out. Switch 44 is closed when a fast start is required which increases the rate of all speed references.
Similarly, during the second and third speed ramps, the output from the amplifier represents the speed reference per ramps 27A and 29A, respectively, and the difference between the actual and reference speeds is compared to the alarm and trip setpoints. Normally, the turbine accelerates along a speed profile such as the profile 46 in FIG. 2. If at any time the actual turbine speed drops to alarm profile 48, an alarm is generated. If the turbine speed drops to trip profile 50, the turbine 12 is tripped.
One main advantage of the described system is that it provides continuous monitoring of the startup acceleration profile without the use of multiple sequence timers. Further, acceleration is monitored with equal resolution at any discrete speed providing better accuracy than discrete sequence timers.

Claims (3)

What is claimed is:
1. An improved acceleration monitoring system for protecting a gas turbine against resonant speed operation, said system comprising means for generating a signal representative of actual turbine speed, means for generating a reference signal which substantially represents desired turbine startup speed as a continuous function of time, means for continuously comparing the actual and reference speed signals and for generating an output representing the difference, means for generating an alarm signal when the difference output reaches a first value which indicates the pssibility of an undesired hold at a resonant speed, and means for generating a turbine trip signal when the difference output reaches a predetermined second value higher than the first value.
2. A system as set forth in claim 1 wherein said reference signal generating means includes first means for generating a first ramp signal having a first slope over a first turbine speed range, second means for generating a second ramp signal having a second slope less than the first slope over a second turbine speed range, and third means for generating a third ramp signal having a third slope less than the second slope over a third turbine speed range.
3. A system as set forth in claim 2 wherein the first speed range is from 0% rated to about 60% rated, the second speed range is from about 60% rated to about 90% rated and the third speed range is from about 90% rated to about 98% rated.
US05/900,946 1978-04-28 1978-04-28 Acceleration monitoring system for protecting gas turbine against damaging operation at resonant speeds Expired - Lifetime US4218878A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US05/900,946 US4218878A (en) 1978-04-28 1978-04-28 Acceleration monitoring system for protecting gas turbine against damaging operation at resonant speeds
CA315,558A CA1110739A (en) 1978-04-28 1978-10-31 Acceleration monitoring system for protecting gas turbine against demaging operation at resonant speeds
GB7913131A GB2020814B (en) 1978-04-28 1979-04-12 Monitoring turbine speed
BR7902432A BR7902432A (en) 1978-04-28 1979-04-20 ACCELERATION MONITORING SYSTEM TO PROTECT A TURBINE AGAINST RESONANT SPEED OPERATION
JP54049185A JPS581251B2 (en) 1978-04-28 1979-04-23 Turbine acceleration monitoring device
IT22041/79A IT1112783B (en) 1978-04-28 1979-04-23 ACCELERATION CONTROL SYSTEM TO PROTECT THE GAS TURBINE FROM HARMFUL OPERATION AT RESONANT SPEED
AR276289A AR221088A1 (en) 1978-04-28 1979-04-24 MONITORING ACCELERATION PROVISION TO PROTECT GAS TURBINES FROM INJURIOUS OPERATION AT RESONANCE SPEEDS
BE0/194893A BE875924A (en) 1978-04-28 1979-04-27 ACCELERATION CONTROL SYSTEM TO PROTECT A GAS TURBINE AGAINST OPERATION AT RESONANCE SPEEDS

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US05/900,946 US4218878A (en) 1978-04-28 1978-04-28 Acceleration monitoring system for protecting gas turbine against damaging operation at resonant speeds

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JP (1) JPS581251B2 (en)
AR (1) AR221088A1 (en)
BE (1) BE875924A (en)
BR (1) BR7902432A (en)
CA (1) CA1110739A (en)
GB (1) GB2020814B (en)
IT (1) IT1112783B (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4337615A (en) * 1979-03-21 1982-07-06 The Garrett Corporation Gas turbine fuel control system
US4619110A (en) * 1983-07-13 1986-10-28 Moore M Samuel Helicopter engine warning or control system
US4817046A (en) * 1986-04-10 1989-03-28 United Technologies Corporation Detection of engine failure in a multi-engine aircraft
US5129221A (en) * 1989-05-23 1992-07-14 Rolls-Royce Plc Gas turbine engine fuel control system with enhanced relight capability
US20040128035A1 (en) * 2002-12-30 2004-07-01 Vandervort Christian L. System and method for steam turbine backpressure control using dynamic pressure sensors
US20060129301A1 (en) * 2004-12-14 2006-06-15 General Electric Company Method and apparatus for assessing gas turbine acceleration capability
CN103452605A (en) * 2013-09-02 2013-12-18 哈尔滨热电有限责任公司 Backpressure protection control method based on DCS (Distributed control system) system
CN103485835A (en) * 2013-10-30 2014-01-01 哈尔滨热电有限责任公司 Backpressure protection control method for 300MW high back pressure unit system
CN103485838A (en) * 2013-09-03 2014-01-01 哈尔滨热电有限责任公司 Protection safety margin and back pressure protection control method used during change of heating steam extraction capacity of 300MW high back pressure unit
CN105888743A (en) * 2016-04-12 2016-08-24 国网上海市电力公司 Supercritical unit DEH side primary frequency modulation method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8818683B2 (en) 2006-04-21 2014-08-26 General Electric Company Method and apparatus for operating a gas turbine engine

Citations (9)

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US3382671A (en) * 1965-12-16 1968-05-14 Beta Corp Control for gas turbine emergency power system
US3469395A (en) * 1965-10-22 1969-09-30 Holley Carburetor Co Gas turbine engine digital fuel control
US3520133A (en) * 1968-03-14 1970-07-14 Gen Electric Gas turbine control system
US3620010A (en) * 1970-02-02 1971-11-16 Gen Electric Gas turbine speed-load control
US3630023A (en) * 1968-10-24 1971-12-28 Honeywell Inc Fluidic engine control apparatus
US3662545A (en) * 1970-08-24 1972-05-16 Gen Electric Acceleration control circuit for a gas turbine
US3911285A (en) * 1973-06-20 1975-10-07 Westinghouse Electric Corp Gas turbine power plant control apparatus having a multiple backup control system
US4010605A (en) * 1974-08-08 1977-03-08 Westinghouse Electric Corporation Accurate, stable and highly responsive gas turbine startup speed control with fixed time acceleration especially useful in combined cycle electric power plants
US4122667A (en) * 1975-12-08 1978-10-31 Nissan Motor Company, Limited System for detecting abnormality in fuel feed control system of gas turbine engine

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Publication number Priority date Publication date Assignee Title
JPS5838782B2 (en) * 1975-08-01 1983-08-25 ミノルタ株式会社 Denshishashin Fukushiyaki
JPS5848600B2 (en) * 1975-09-08 1983-10-29 バブコツク日立株式会社 Cement clinker

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3469395A (en) * 1965-10-22 1969-09-30 Holley Carburetor Co Gas turbine engine digital fuel control
US3382671A (en) * 1965-12-16 1968-05-14 Beta Corp Control for gas turbine emergency power system
US3520133A (en) * 1968-03-14 1970-07-14 Gen Electric Gas turbine control system
US3630023A (en) * 1968-10-24 1971-12-28 Honeywell Inc Fluidic engine control apparatus
US3620010A (en) * 1970-02-02 1971-11-16 Gen Electric Gas turbine speed-load control
US3662545A (en) * 1970-08-24 1972-05-16 Gen Electric Acceleration control circuit for a gas turbine
US3911285A (en) * 1973-06-20 1975-10-07 Westinghouse Electric Corp Gas turbine power plant control apparatus having a multiple backup control system
US4010605A (en) * 1974-08-08 1977-03-08 Westinghouse Electric Corporation Accurate, stable and highly responsive gas turbine startup speed control with fixed time acceleration especially useful in combined cycle electric power plants
US4122667A (en) * 1975-12-08 1978-10-31 Nissan Motor Company, Limited System for detecting abnormality in fuel feed control system of gas turbine engine

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4337615A (en) * 1979-03-21 1982-07-06 The Garrett Corporation Gas turbine fuel control system
US4619110A (en) * 1983-07-13 1986-10-28 Moore M Samuel Helicopter engine warning or control system
US4817046A (en) * 1986-04-10 1989-03-28 United Technologies Corporation Detection of engine failure in a multi-engine aircraft
US5129221A (en) * 1989-05-23 1992-07-14 Rolls-Royce Plc Gas turbine engine fuel control system with enhanced relight capability
DE10361755B4 (en) * 2002-12-30 2010-12-16 General Electric Co. Backpressure monitoring system and method for steam turbines using dynamic pressure sensors
US20040128035A1 (en) * 2002-12-30 2004-07-01 Vandervort Christian L. System and method for steam turbine backpressure control using dynamic pressure sensors
US6865935B2 (en) * 2002-12-30 2005-03-15 General Electric Company System and method for steam turbine backpressure control using dynamic pressure sensors
CN1329721C (en) * 2002-12-30 2007-08-01 通用电气公司 System and method for steam turbine backpressure control using dynamic pressure sensors
US20060129301A1 (en) * 2004-12-14 2006-06-15 General Electric Company Method and apparatus for assessing gas turbine acceleration capability
CN103452605A (en) * 2013-09-02 2013-12-18 哈尔滨热电有限责任公司 Backpressure protection control method based on DCS (Distributed control system) system
CN103485838A (en) * 2013-09-03 2014-01-01 哈尔滨热电有限责任公司 Protection safety margin and back pressure protection control method used during change of heating steam extraction capacity of 300MW high back pressure unit
CN103485835A (en) * 2013-10-30 2014-01-01 哈尔滨热电有限责任公司 Backpressure protection control method for 300MW high back pressure unit system
CN105888743A (en) * 2016-04-12 2016-08-24 国网上海市电力公司 Supercritical unit DEH side primary frequency modulation method

Also Published As

Publication number Publication date
CA1110739A (en) 1981-10-13
IT1112783B (en) 1986-01-20
GB2020814B (en) 1982-08-25
JPS581251B2 (en) 1983-01-10
JPS54145810A (en) 1979-11-14
BR7902432A (en) 1979-10-23
AR221088A1 (en) 1980-12-30
IT7922041A0 (en) 1979-04-23
GB2020814A (en) 1979-11-21
BE875924A (en) 1979-10-29

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